NEW YORK (Reuters Health) - Many people take multivitamins in the hopes of thwarting disease, but a new study finds that older women who use multivitamins may be more likely than non-users to develop breast cancer.

In the U.S., for example, it's estimated that half of adults routinely use a dietary supplement, often a multivitamin. And studies show that one of the primary motivations is the belief that supplements will protect them from chronic diseases.

In a decade-long study of more than 35,000 Swedish women who were between the ages of 49 and 83 and cancer-free at the outset, researchers found that women who reported multivitamin use at the study's start were 19 percent more likely than non-users to develop breast cancer. That was with factors like age, family history of breast cancer, weight, fruit and vegetable intake, and exercise, smoking and drinking habits taken into account.Until more is known, a woman's best bet is to get her vitamins and minerals from a well-balanced diet rather than pills, advised lead researcher Dr. Susanna C. Larsson, of the Karolinska Institute in Stockholm.

"If you eat a healthy and varied diet," she said, "there is no need to use multivitamins."